Heat storage control system



Dec. 16, 1941. c OSTERHELD 2,266,257

HEAT STORAGE CONTROL SYSTEM Filed Sept. 6, 1941 2 Sheets-Sheet 2 CLARKJSNZEE/ZSZD ATTORNEY Patented Dec. 16, 1941 HEAT STORAGE CONTROL SYSTEM Clark M. Osterheld, Stoughton, Wis., assignor to McGraw Electric Company, Elgin, 111., a corporation of Delaware Application September 6, 1941, Serial No. 409,817

8 Claims. (Cl. 219-39) My invention relates to house heating systems and particularly to systems for controlling the storage of electrically generated heat in heat storing masses.

An object of my invention is to provide a control system for effecting the energization of an electric heater for generating and storing heat mainly during off-peak periods.

Another object of my invention is to provide a control system for storing heat in heat storing masses operable to cause a fixed delay after the start of an off-peak period in case the temperature oi the heat storage mass is above a given value and to start energization of the heater at the start of an off-peak period in case the temperature of the heat storage mass is below a given value.

'Other objects of my invention will either be apparent from a description of several forms of systems embodying my invention or will be pointed out in the course of such description and set forth in the appended claims.

In the drawings,

Figure 1 is a diagrammatic representation of one control system embodyin my invention as applied to a heat storage mass having associated therewith air-moving means and as applied to a dwelling,

Fig. 2 is a schematic diagram of connections of another control system embodying my invention, with certain of the details shown in Fig. 1 omitted,

Fig. 3 is still another diagram of connections embodying my invention as applied to a heat storage mass, and,

Fig. 4 is a still further modification of a heat storing control system embodying my invention.

House heating is being effected by air-moving or ventilating means, the heated air deriving its heat from a heat storage mass which, in some instances, has been simply a mass of say metal, positioned within a suitable heat insulated enclosure, having electric heating means operatively associated therewith and a ventilating or air-moving fan of suitable design controlled by one or more thermostats at least one of which would be in a room representative of the average temperature conditions of a house.

Since central stations or public utilities furnishing current to users have a period of relatlvely light load, usually extending from say 10 or 11 p. m. to about 6 or 7 a. m., they are willing to make a reduced rate for electric energy when used at such an oil-peak period, particularly so it the load or loads are applied to the system at the time of maximum drop in the load or, to put it in another way, at the time of really minimum load on the power house.

Referring first to Fig. 1 of the drawings, I have there illustrated an enclosure l I which is adapted to receive a mass l3 of heat storage material which is indicated generally only in broken lines and is to be understood as being made up of any suitable or desired material in any suitable, desired or available shapes, it being understood, of course, that it must be possible to heat substantially all of the mass to a predetermined average temperature without too great a variation in the temperatures of different parts of the heat storage mass and that it must be possible to move air through the heat storing mass, out of the enclosure and into the room or rooms where it is to be used to maintain the temperature at a desired value, say 70 F. to 75 F. Since the details of the construction of the enclosure and the details of construction of the heat storage mass form no part of my invention, they are shown generally only.

A conduit 15 connects the enclosure H with say the floor ll of a room or the floor of any building having a room IE! or rooms to be heated.

The enclosure II is provided also with an air inlet opening N in which, in suitable and proper position, there is positioned a motor driven Ian 23 adapted to force air over or through the heat storage mass l3 and it is to be understood that while this inlet 2| is shown as of relatively short length, it may be of any size, contour and length value, will operate to force cold or cool air through the heat storage mass [3 and into the room l9 until the temperature in that room has caused the thermostat 25 to move to the position shown in Fig. 1 of the drawings when the fan motor will be deenergized and remain so until the temperature in the room or other area to which thermostat 25 is responsive drops an amount sufllcient to cause reclosing of the thermostat 25.

I provide a continuously operative timer 3| here shown as comprising a small electric motor 33 connected to the supply circuit conductors 21 and 29 and having a worm 35 on the shaft which meshes with and drives a worm gear 31 which is secured to a shaft 39.

A cam disk 4| is mounted on shaft 39 and may be secured thereon in such manner as to be shiftable peripherally thereof. The greater part of the radius of cam disk 4| is of constant outer radius but the cam includes also a portion 43 of somewhat larger radius and this cam surface or portion is in effect, the off-peak portion and is shown as extending over substantially one-third of the periphery. Since I have shown the driving mechanism for the cam4l generally only, I desire to state here that it is desired to cause one complete revolution of the cam disk 4| in twenty-four hours, so that the off-peak portion will extend over substantially eight hours and the cam disk may be so set on shaft 39 that the ofi-peak portion 43 operates to close a switch, to be hereinafter described in detail, at p. m. and causes opening of this switch at say 6 a, m. While I have shown and prefer to use an electric motor, I do not desire to be limited thereto, but may use any other kind of constantly operative timer eflective for. the

same purpose. a

I provide further a second cam disk 45 adjacent to and at one side of cam disk 4|, the greater portion of the periphery of this cam disk 45 being of uniform radius but having a small portion 41 of smaller radius. I may point out here that the peripheral extent of portion 41 is such as to amount to two or three hours out of the total of twenty-four hours, it being understood that cam disk 45 will also turn through one complete revolution in twenty-four hours.

I provide a first timer controlled switch including a substantially rigid contact arm 49 and a resilient contact arm 5| which latter is normally biased out of engagement with arm 49 but is moved into engagement with it when a lug 53, of electric-insulating material, on contact arm 5| engages portion 43 of cam disk 4|. The switch including contact arms 49 and 5| is shown in its closed position and the time is therefore just a little after 10 p. m.

I provide an auxiliary timer-controlled switch including a substantially rigid contact arm 55 and a resilient contact arm 51 normally yieldingly biased out of engagement with arm 55 in which position it is shown in Fig. l of the drawings since a lug 59, of electric-insulating material, on arm 51 has entered the portion 41 of lesser outer radius than the rest of cam 45. It will be understood that when lug 59 rides upon the other part of cam disk 45, of the greater radius, contact arm 51 will be in engagement with arm 55.

I provide an electric heater 6| which I have illustrated as being positioned in the enclosure or casing and have indicated it generally only since the details of construction and location thereof form no part of my present invention.

I provide a main thermal switch 63 here shown as including a bi-metallic bar 65 having one end fixed and the other end adapted to engage with or be disengaged from a contact member 61. I provide further an auxiliary thermal switch 69 which may include a bimetal bar 1| having one end fixed to a contact member and adapted to engage with or be disengaged from a fixed contact 13.

A conductor 15 connects supply circuit conductor 21 with contact arm 5| while contact arm 49 is connected by a conductor 11 with bimetal bar 1|. Contact member 13 is connected by a conductor 19 with bimetal bar 65 and contact 61 is connected by a conductor 8| to one terminal of heater 5|, the other terminal of which is connected by a conductor 83 with supply circuit conductor 29. Contact arm 49 is connected by a conductor 85 with contact arm 55 while contact arm 51 is connected by a conductor 81 with contact 13 and therefore with conductor 19.

It is to be noted that the main thermal switch 63 is designed, constructed and adjusted to cause bimetal bar 65 to move out of engagement with fixed contact member 61 at substantially 800 F. but to remain in contact therewith until the temperature to which it is responsive is substantially 800 F. The auxiliary thermal switch 69 is designed, constructed and adjusted so that the bimetal bar 1| will remain in engagement with fixed contact 13 until substantially a temperature of 500 F. is ambient thereto, at which time it will move out of engagement with contact 13.

Let it be assumed that the time is a few minutes after 10 p. m. and that the parts of the system are in substantially the positions shown in Fig. 1 of the drawings. Since both the main and the auxiliary thermal switch are in closed positions, which means that the temperature of the heat storage mass is below 500 F., energization of the heater 6| will be effected at the start of an off-peak period, that is, as soon as contact arm 5| is moved into engagement with contact arm 49 which, as has been above set forth, has occurred at say 10 p. m. The energizing circuit through heater 6| may be traced as follows: From supply circuit conductor 21 through conductor 15 to contact arm 5|, from there to contact arm 49, through conductor 11 to and through bimetal bar 1|, contact 13, conductor 19, bimetal bar-65, contact 61 and from there through conductor 8| to and through heater 9| and from there through conductor 83 to the other supply circuit conductor 29. It is, therefore, evident that energization of the heater 6| will be effected immediately at the start of an off-peak period and the design, construction and adjustment of all the parts of my improved control system is to be understood as being such that heating of the heat storage mass l3 to substantially 800 F. will be effected substantially within an off-peak period since it s evident that disengagement of contact arm 5| from contact arm 49 will deenergize the system and, as has already been set forth, this will occur when lug 53 rides off of portion 43 of cam disk 4|.

Let it be assumed, in order to show the operation of my improved control system, that while the temperature of the heat storage mass is less than 800 F., its temperature is above 500 F. so that bimetal bar 1| is flexed out of engagement with contact 13. In this case engagement of contact arm 5| with contact arm 49 by the timercontrolled means would not cause energization of the heater 6| at the start of an off-peak period. It will be noted, however, that when contact arm 51 is moved into engagement with contact arm 55, by engagement of lug 59 with the leading edge of portion 45, which will occur at say 12 midnight or 1 a. m., an energizing circuit through the heater 6| will be established as follows: From supply circuit conductor 21 through conductor 15 to contact arm 5| to and through contact arm 49, conductor 85, contact arms 55 and 51 which are now in engagement with each other, through conductors 31 and 19, through bimetal bar 95 and contact 91 and from there through conductor 9| and the electric heater 9| and conductor 93 to the other supply circuit conductor 29. This energization of heater 9| is therefore effected at a fixed time or after a fixed delay period after the start of an off-peak period and this energization will continue until either mechanically terminated by disengagement of contact arm 5| from arm 49 at the end of an off-peak period or by flexing of bimetal bar 55 when the temperature of the heat storage mass to which the main thermal switch 93 responds has reached substantially 800 F. It is, therefore, evident that energization of the heater 9| is selectively terminated either by the contact arms II and 49 being moved out of engagement with each other at the end of an off-peak period or at some time before the end of but during an oil-peak period, by warping or flexing movement of the main thermal switch 63.

Referring now to Fig. 2 of the drawings, I have there shown the enclosure or casing I I, the heat storage mass I3, and the main thermal switch 63 which is of the same construction and method of operation as has hereinbefore been described in connection with Fig. 1 of the drawings. I provide an auxiliary thermal switch 99 including a bimetal bar 9| having one end secured to a fixed contact member while the other end thereof is adapted to engage with and be disengaged from a fixed contact member 93. The auxiliary thermal switch 99 is designed, constructed and adjusted to be in open position at all temperatures below substantially 500 F. and to close or to have the bimetal bar 9| engage contact member 93 at temperatures above 500 F.

A continuously operative timer 95 includes an electric motor 91 having a worm 99 on its shaft adapted to mesh with and drive a worm gear |I which is mounted on a shaft I03. While I have shown a simplified mechanical driving means it is to be understood that this is general and representative only, the object being to cause rotation of say, shaft I03, through one whole or complete revolution in twenty-four hours. I mount a cam disk 4| on shaft I03 which is substantially the same as has hereinbefore been described in connection with Fig. 1. I provide an auxiliary cam disk I adjustably secured on shaft I03 the greater part of the periphery being of substantially uniform radius but having a relatively short portion I01 of slightly larger radius and extending over substantially two to three hours as may be desired.

I provide a main timer-controlled switch including a substantially rigid contact arm I09 and a resilient contact arm III normally yieldingly biased out of engagement with contact arm I09 but adapted to be moved into engagement therewith when a lug II3 on arm III is engaged by the leading edge of portion 43 of cam disk 4|. I provide also an auxiliary timer-controlled switch including a substantially rigid contact arm H5 and a resilient contact arm II1 normally yieldingly biased out of engagement with arm I I 5 but adapted to be moved into engagement therewith when a lug N9 of electric insulating material on arm II1 engages portion I01 of auxiliary cam disk I05.

I provide also an electromagnetic switch I2I to control the energization of the heater GI and this electromagnetic switch or contactor includes a coil I23 and a movable armature core I25 connected to a contact bridging member I21 which is adapted to engage with or be disengaged from two fixed contact members I29, all in a manner well known in the art.

A conductor I3I connects supply circuit conductor 21 to contact arm III and a conductor I33 connects arm I09 to one of the fixed contacts I29. The other fixed contact I29 is connected by a conductor I35 to one terminal of the heater 6|, the other terminal of which is connected by a conductor I31 with bimetal bar 95. The contact member 61 of main thermal switch 63 is connected by a conductor I39 to the other supply circuit conductor 29. Contact arm III is connected by a conductor |4I with contact arm H5 and contact arm H1 is connected by a conductor I43 with contact member 93 of the auxiliary thermal switch 99. One terminal of coil I23 of the contactor |2| is connected by a conductor I44 to the fixed contact of bimetal bar 9| and the other terminal of coil I23 is connected by a conductor I45 to conductor I31 and therefore to the fixed contact of bimetal bar 65.

Let it be assumed that the bimetal bars and 9| are in engaged positions as shown in Fig. 2 of the drawings so that the temperature of the heat storage mass is somewhat above 500 F. but below 800 F. When the main and the auxiliary timer-controlled switches are closed as shown in Fig. 2 of the drawings, which will occur at substantially 10 p. m., an energizing circuit through coil I23 will be established as follows: From supply circuit conductor 21 through conductor I3I, to arm III, through conductor |4| to and through the engaged contact arms H5 and H1, through conductor I43 to contact 93, engaged bimetal bar 9|, through conductor I44 and coil I23 of contactor I2I, through conductor I45 to bimetal bar 65, to and through contact 61 and from there through conductor I39 to the other supply circuit conductor 29. This will energize coil I23 and cause upward movement of contact bridging member I21 out of engagement with fixed contacts I29 whereby energization of heater BI is prevented.

It is obvious that should the temperature of the heat storage mass be below 500 F., bimetal bar 9| would be out of engagement with contact 93 and the above described energizing circuit of coil I23 of the heater control switch |2I would not have been established, with the result that contact bridging member I21 would be in engagement with fixed contacts I 29 and an energizing circuit through the heater 6| would be established substantially as follows: From supply circuit conductor 21 through conductor I3I, to and through the engaged contact arms I09 and III, through conductor I33 to and through the engaged contacts I29 and I21, through conductor I35, heater 6|, through conductor I31 to and through the main thermal switch 93 and from there through conductor I39 to the other supply circuit conductor 29. In this case energization of the heater 6| will be started at substantially the beginning of an off-peak period and it may occur that the average temperature of the heat storage mass reaches 800 F. a short time before the end of an off-peak period in which case bimetal bar 65 of the main thermal switch 93 will move out of engagement with contact 61 and deenergize the heater 6 I Let it be assumed, however, that both the main and the auxiliary thermal switch were in closed positions at the start of an ofi-peak period, as shown in Fig. 2 of the drawings, so that the contactor is open and the heater is deenergized during the initial part of an off-peak period. In this case auxiliary switch comprising contact arms H1 and H5 would be moved to open position as soon as lug H9 would ride of! of the portion I01 of increased radius of the auxiliary cam disk I05 which, as has hereinbefore been stated, might be at I2 midnight or thereabouts and when this Occurs the hereinbefore described energizing circuit through coil I23 of contactor |2| would be interrupted and contact bridging member I21 would drop down into engagement with fixed contacts I29 to establish the hereinbefore described energizing circuit through heater 6|. Here again it may be that disengagement of lug H3 on arm from the portion 43 of the main cam disk 4| at the end of an ofi-peak period might deenergize the heater assuming that the temperature of the heat storage mass had not yet reached 800 F. On the other hand, should the average temperature of the heat storage mass have reached 800 F. before the end of an offpeak period, the main thermal switch 63 would be effective to deenergize the heater 6|.

Referring now to Fig. 3 of the drawings, I have there illustrated a further modification of a control system embodying my invention. This system includes a main thermal switch 63 with the parts as described hereinbefore in connection with Fig. 1, an auxiliary thermal switch 89 and 1 a continuously operative timer 3| including more particularly the electric motor driving means and other parts hereinbefore described to cause one complete revolution of a shaft 39 in twenty-four hours. mounted on shaft 39 the greater portion of the periphery of disk I41 being of uniform outer radius but having a relatively short portion I49 of slightly greater outer radius and a second portion I5I of still greater outer radius. The peripheral extent of portion I49 may be on the order of two or three hours and the peripheral extent of portion |5| may be such that the total peripheral extents of these two portions equal the length of an off-peak period which, as has hereinbefore been mentioned, may be on the order of eight hours.

I provide further a triple contact arm switch driven by the timer and comprising a substantially rigid outer contact arm I53 and an intermediate contact arm |55 normally yieldingly biased out of engagement with contact arm I53. I provide further a second outer contact arm I51 normally yieldingly biased out of engagement with contact arm I55 but adapted to be moved into engagement with arm I55 when 2. lug I59, of electric insulating material, on arm I51 engages the leading edge of portion I49. Contact arm I55 is adapted to be moved into engagement with contact arm I53 when lug I59 engages the leading edge of portion |5| of cam disk I41.

I provide further an electromagnetic switch or contactor I6I including a coil I63 and a movable core I65 connected to a contact bridging member I61, which latter is adapted to engage with and be disengaged from fixed contact members I69.

A conductor |1| connects supply circuit conductor 21 with contact arm I51 and a conductor I13 connects contact arm I55 with contact 93 of the auxiliary thermal switch 89. Conductor III is connected by a conductor I15 with one of the fixed contact members I69 while the other fixed contact member I69 is connected by a con ductor I11 with one terminal of heater 6|.

I provide a cam disk I 41 adjustabiy The other terminal of heater 6| is connected by a conductor I19 with bimetal bar 65 and fixed contact 61 is connected by a conductor I6| with the other supply circuit conductor 29. One terminal of coil I63 is connected by a conductor I83 with contact arm I53 and a conductor I85 connects the same terminal to the fixed end of bimetal bar 9|. The other terminal of coil I63 is connected by a conductor I61 to conductor I19 and therefore to the fixed end of bimetal bar 65.

Let it be assumed that the time is shortly after 10 p. m. so that contact arm I51 is in engagement with contact arm I55 and further that the temperature of the heat storage mass to which auxiliary switch 89 is responsive is above 500 F. so that bimetal bar 9| is out of engagement with fixed contact 93. No energization of coil 63 of contactor |6| can therefore occur and energizetion of the heater will not be affected at this time through the contacts of switch I6I.

Let it be assumed now that enough time has elapsed so that lug I59 has engaged on or with the leading edge of portion |5I whereby intermediate contact arm |55 has been moved into engagement with contact arm I53. An energizing circuit through coil I63 will now be effected as follows: through conductor Hi, to contact arm I51, from there through the contacts of arm I55 to the contact of arm I53, from there through conductor I83 through coil I63, through conductor I81 to and through the main thermal switch 63 and from there to and through conductor |6| to the other supply circuit conductor 29. This will energize coil I63 and cause quick upward movement of contact bridging member I61 thereby establishing an energizing circuit through heater 6| substantially as follows: From supply circuit conductor 21 through conductors HI and I15, to and through the engaged contacts I61 and I69, through conductor I11 to and through heater 6|, from there through conductor I19 to and through thermal switch 63 and from there through conductor I8| to the other supply circuit conductor 29.

It is, therefore, evident that under these conditions energization of the heater 6| will be effected after a fixed time delay after the start of an off-peak period and will continue until the heater 6| is selectively deenergized either by opening of the main thermal switch 63 or opening of the timer-controlled switch at.the end of an off-peak period.

I may further point out that energization of the heater 6| will be effected at the start of an off-peak period in case auxiliary thermal switch 89 is in closed position when, at the start of an oil-peak period, contact arm I51 is moved into engagement with contact arm I55. The energizing circuit through coil I63 will be substantially as follows: From supplycircuit conductor 21 through conductor "I to and through the engaged contact arms I 51 and I55, through conductor I13 to and through the closed auxiliary thermal switch 89, through conductor I85 to and through coil I63 and conductor I81 to and through the main thermal switch 63 and from there through conductor I8I to the other supply circuit conductor 29. This will cause closure of the electromagnetic switch |6| and consequent energization of heater 6| all as has hereinbefore been described. The same conditions as to selective deenergization of heater 6| are present as were hereinbefore described so that if the heat storage mass I3 reaches a temperature of 800 F.

From supply circuit conductor 21 before the end of an off-peak period, the heater will be deenergized by opening of the main thermal switch 33. If the temperature of the heat storage mass is still less than 800 F. at the end of an oil-peak period, main thermal switch 93 would still be in closed condition and deenergization of heater 3| would be eflected by the action of the timer-actuated switch including contact arms I53, I55,and I51.

Referring now to Fig. 4 of the drawings, I have there shown a still further modification of a system embodying my invention the constantly operative timing means being substantially the same as set forth and shown in connection with Fig. 3. I provide also a main thermal switch 63 as has hereinbefore been described and an auxiliary thermal switch 69 as described in connection with Fig. 1.

I provide a contactor I99 including a coil I9I and a movable core I93 to which are attached two contact bridging members I95 and I91. Bridging member I95 is adapted to be engaged with or disengaged from fixed contact members I99 and bridging member" I91 is adapted to engage with or be disengaged from fixed contact members 20I.

I provide also means for recording the electric energy used by electric heater 6I on a low-rate meter 203 or on a high-rate meter 205 since the system shown in Fig. 4 of the drawings may continue the energization of heater beyond the nd of an oiT-peak period and it is, of course, desirable to record the electric energy used during an on-peak period on a high-rate meter. I provide a solenoid having a coil 201 adapted to energize a core 299 the lower end of which is connected to a pivotally mounted switch arm 2I I adapted to engage either one of two fixed contact members 2I3 and 2I5, under the control of coil 201 and its core 209. Supply circuit conductor 21 is connected by a conductor 2I1 to contact arm I51 and to one each of the contact members 20I and I99. The other fixed contact member MI is connected by a conductor 2I9 with contact 51 of the main thermal switch 63. Fixed contact member 13 of the auxiliary thermal switch is connected by a conductor 22I with one terminal of coil I9I, the other terminal of which is connected by a conductor 223 with a conductor 225 connecting one terminal of coil I9I with the pivot point of switch arm 2. Contact 2I5 is connected to one terminal of meter 205 by a conductor 221 and contact 2I3 is connected by a conductor 229 with one terminal of meter 203, the other terminals of meters 203 and 205 being connected together and to supply circuit conductor 29 by a conductor 23I.

Contact arm I55 is connected by a conductor 233 to the fixed end of bimetal bar H of auxiliary thermal switch 59. Contact arm I53 is connected by a conductor 235 to the other terminal of coil I9I. Conductor 225 is connected to one terminal of coil 201 by a conductor 231 and the other terminal of coil 201 is connected by a conductor 239 with contact arm I55.

In order to provide means for manually causing energization of the system during an off-peak period in case of necessity, I provide a normally open push button switch 24I of the usual kind, one terminal of which is connected by a conductor 243 with one terminal of coil I9I and to conductor 22I. The other terminal of switch 24I is connected by a conductor 245 with conductor 2I1.

Let it be assumed that the temperature of the heat storage mass at the start of an oil-peak period is below 800 1". but above 500 P. so that the auxiliary switch will be in its open position as shown in'Fig. 4 of the drawings. When contact arm I51 is moved into engagement with contact arm I55 by the leading edge of portion I49 of cam disk I41, energization of coil I9I through a circuit to be hereinafter described will not be closed since it is open at the auxiliary thermal switch 99.

However, an energizing circuit through coil I9I will be closed at the end of a fixed delay period after the start of an off-peak period when intermediate contact arm I55 is moved Into engagement with the outer contact arm I53 when lug I59 engages the leading edge of portion I5I of cam I41. -As stated before, this will occur at say two or three hours after the start of an oil'- pealr period. The energizing circuit through coil I9I is established substantially as follows: From supply circuit conductor 21 to conductor 2I1, through the engaged contacts of contact arms I51, I55 and I53, through conductor 235 through coil I9I and from there through conductor 223 to conductor 225 and from there through switch 2 through either the low-rate meter 203 or the high-rate meter 205 and conductor 23I to the other supply circuit conductor 29. This will energize a circuit through heater 6| substantially as follows: From supply circuit conductor 21 to and through conductor 2I1, to and through the engaged contact members I and I99, through conductor 245 to one terminal of heater SI and from there through heater SI and conductor 225 to the other supply circuit conductor 29 through switch arm 2I I in engagement with fixed contact member 2I3, through conductor 229 and through low-rate meter 203 and conductor 23I to th other supply circuit conductor 29.

The low-rate meter 203 will be connected in circuit with heater 9| because of the energization of coil 201 through a circuit substantially as follows: From supply circuit conductor 21 through conductor 2I1 to contact arm I51, to contact arm I55 through conductor 239, coil 201 and conductor 231 to conductor 225. Even if switch arm 2 were in its other position where it would engage contact member 2I5, it would still be connected through the high-rate meter with the other supply circuit conductor 29 so that the above described energizing circuit through coil 201 would be established and switch arm 2 would be moved into engagement with contact 2I3. It may here be pointed out that arm 2II is made wide enough to simultaneously engage contact members 2I5 and 2I3 at the time of its movement so that energization of the circuit or connection of the parts with supply circuit conductor 29 will not be interrupted.

Let it now be assumed that at the start of an off-peak period auxiliary thermal switch 59 was in closed position because the temperature of the heat storage mass was below 500 F. An energizing circuit through the coil of electromagnetic switch I89 would have been established at the start of an oil-peak period, this circuit being substantially as follows: From supply circuit conductor 21 through conductor 2I1, through engaged contact arms I 51 and I55, through conductor 233 to and through closed auxiliary thermal switch 69, through conductor 22I, through coil I9I and then through conductor 223 to conductor 225 which, as has hereinbefore been stated, will be electrically connected to the other supply circuit conductor 29 by parts and conductors already set forth. In this case energization of the heater 6| will be effected, at the start of an off-peak period and engagement of the timer-controlled switch with portion II of cam I" will have no other effect on the system. The deenergization of heater 6I will be effected by the main thermal switch 63 at a time before the end of an oiT-peak period if the temperature of the heat storage mass reaches substantially 800 F. before the end of an off-peak period.

A holding circuit through coil I9| of contactor I89 is established at the time of energization of coil I! and this holding circuit may be traced as follows: From supply circuit conductor 21 through conductor 2" to and through the engaged contact members I91 and 2IlI through conductor 2I9 to and through the closed main thermal switch 63, through conductors I9 and MI to and through coil I9I and from there through conductor 223 to conductor 225 and from there to the other supply circuit conductor 29. In case, therefore, that the temperature of the heat storage mass is still below a value of substantially 800 F. at the end of an off-peak period when contact arms I51, I55 and I53 are moved out of engagement with each other, the holding circuit being independent of the timer-controlled switch, and controlled particularly by the main thermal switch 63, the contactor I89 will be held in such position that energization of the heater 6| will be continued beyond the end of an offpeak period. This energization will continue until bimetal bar 65 moves out of engagement with contact 6'! which, of course, will occur when the heat storage mass reaches a temperature of substantially 800? F., at which time coil 20'! is deenergized and high-rate meter 205 is connected in circuit.

Let it now be assumed that because of some abnormal condition it is desired to effect energization of the heater 6| during the period extending from about 6 a. m. to 10 p. m. In this case all that is necessary for the operator or user to do is to press momentarily on the contact bridging member of push button switch 2 when an energizing circuit through coil I9I of contactor I89 will be established substantially as followsfi From supply circuit conductor 21 through conductors 2H and 245, through the closed switch 2, through conductor 243 and coil I9I and from there through conductor 223 to conductor 225 and from there through the parts between the end of conductor 225 and supply circuit conductor 29. This momentary energization of coil I9I of electromagnetic switch I89 will cause movement of the main and the auxiliary contact bridging members of switch I89 into engagement with the fixed contact members whereby the hereinbefore described energizing circuit through heater BI and the holding circuit through coil I9I will be effected whereby the user can generate heat and store it in the heat storage mass as might conceivably be necessary in case of a sudden great drop of temperature.

It is to be pointed out here further that the coil of solenoid 201 is effective to cause proper connection in circuit with the heater 6| of a low-rate meter or a high-rate meter, the control of the energization of solenoid 201 being by the timer-controlled switch including more particularly the contact arms I51 and I55. It is to be pointed out further that the end of conductor 225 connected to the pivotally supported switch arm 2 is always in electrical engagement with or electrically connected to the other supply circuit conductor 29 and where 1 have stated that energization of a given circuit was eifected through conductor 223 or conductor 231, it is to be understood that the same statement applies as to being connected to the other supply circuit conductor 29.

The various modifications of systems embodying my invention and shown in the various figures of the drawings therefore provide relatively simple systems effective for the intended purpose, namely to cause energization of the electric heater and attendant storage of heat in a heat storage mass at the start of an off-peak period in case the temperature of the heat storage mass at the start of an off-peak period is less than a predetermined value or to start energization of the heater after a fixed delay time interval after the start of an off-peak period in case the temperature of the heat storage mass is above said predetermined value. Several forms of systems embodying my invention effect deenergization of the electric heater at the end of an off-peak period and no further heat can be stored in the heat storage mass until the start of the next ofi-peak period.

One of the systems embodying my invention, namely that shown in Fig. 4, is effective to prolong the energization of the electric heater beyond the termination of an off-peak period in case the temperature of the heat storage mass is still below the desired value and this system further permits of the user efi'ecting energization of the system and generation of heat with attendant storage of such heat at any time during the rest of the day should this become necessary.

Reference may now be made to means for preventing flow of air through the heat storage mass I3 at those times when the fan 23 is not operating, shown in Fig. 1. This means includes a damper plate 25I pivotally supported in the conduit between the enclosure II and the room I9 and controlled by a solenoid 253 connected in series electric circuit with the fan motor 23 and its controlling room thermostat 25. A biasing spring 255 tends to hold the damper 25I closed as shown in Fig. 1, this being the position which the damper plate will take when the room is above a given temperature and the thermostat 25 is open. This will prevent the fiow of undesired convection currents of air through the heat storage mass at those times when the mass is being heated and also during those periods of the day when the room is at the desired temperature, thereby conserving heat in the heat storage mass.

Various modifications may be made in my invention without departing from the spirit and scope thereof and all such obvious modifications clearly coming within the scope of the appended claims shall be considered to be covered thereby.

I claim as my invention:

1. An off-peak heat storage system for heating a heat storage mass comprising an electric heater for said mass, a continuously operative timer, switching means controlled jointly by said timer and by the temperature of said heat storage mass for selectively causing energization of said heater at the start of an off-peak period in case the temperature of the storage mass is below a set value and to delay the energization of said heater for a given time interval in case the temperature of the heat storage mass is above said set value.

2. An off-peak heat storage system for heating a heat storage mass comprising an electric heater for said mass, a continuously operative timer,

time and temperature controlled switching means to selectively effect energization of said heater at substantially the start of an off-peak period in case the temperature of the heat storage mass is below a predetermined value and to delay the energization of said heater for a preset fixed length of time in case the temperature of the heat storage mass is above said predetermined value at the start of an off-peak period and remains above said predetermined value during said delay period.

3. An oiT-peak heat storage system for heating a heat storage mass comprising an electric heater for said mass, a continuously operative timer, time and temperature controlled switching means to selectively effect energization of said heater at substantially the start of an offpeak period in case the temperature of the heat storage mass is below a predetermined Value, to prevent energization of the heater at the start of an ofi-peak period in case the temperature of the heat storage mass is above said predetermined value at the start of an ctr-peak period and to effect energization of said heater after a fixed time interval after the start of an off-peak period in case the temperature of the heat storage mass is below a second higher predetermined temperature.

4. An oil-peak heat storage system for heating a heat storage mass comprising an electric heater for said mass, a continuously operative timer, switching means controlled jointly by said timer and by the temperature of said heat storage mass for selectively causing energization of said heater at the start of an off-peak period in case the temperature of the storage mass is below a set value and to delay the energization of said heater for a given time interval in case the temperature of the heat storage mass is above said set value and a thermally-actuable switch for causing deenergization or said heater when the temperature of said heat storage mass has been raised to a predetermined high value.

5. An oil-peak heat storage system for heating a heat storage mass comprising an electric heater for said mass, a continuously operative timer, time and temperature controlled switching means to selectively effect energization of said heater at substantially the start of an offpeak period in case the temperature of the heat storag mass is below a predetermined value, to

prevent energization of the heater at the start,

of an off-peak period in case the temperature of the heat storage mass is above said predetermined value at the start of an off-peak period and to eflect energization of said heater after a fixed time interval after the start of an off-peak period in case the temperature of the heat storage mass is below a second higher predetermined temperature and a thermally-actuable switch for causing deenergization of said heater when the temperature of said heat storage mass has been raised to a predetermined high value.

6. An oil-peak heat storage system for heating a heat storage mass, comprising an electric heater for said mass, an electromagnetic heater control switch, switches controlled respectively by time and by the temperature of the heat storage mass for controlling said electromagnetic switch to selectively cause energization of said heater at the start of an oil-peak period in case the temperature of said heat storage mass is below a given value, to delay the energization of said heater after the start of an oil-peak period in case the temperature of said heat storage mass is above said given value and to cause energization of said heater after a preset time interval after the start of an off-peak period in case the temperature of the heat storage mass is less than a second given value higher than said first given value.

7. An off-peak heat storage system for heating a heat storage mass, comprising an electric heater for said mass, an electromagnetic heater control switch, switches controlled respectively by time and by the temperature of the heat storage mass for controlling said electromagnetic switch to selectively cause energization of said heater to be delayed after the start of an oilpeak period in case the temperature of said heat storage mass is above a predetermined value and to be effected as soon as withdrawal of heat from said heat storage mass causes its temperature to drop below said predetermined value, a thermal switch responsive to the temperature or said heat storage mass for causing deenergization of said heater when the temperature of said heat storage reaches a second predetermined value higher than said first predetermined value, and a normally open switch adapted to be momentarily closed to cause the electromagnetic switch to energize said heater during the on-peak period.

8. An oil-peak heat storage system for heating a heat storage mass comprising an electric heater for said mass, a continuously operative timer, time and temperature controlled switching means to selectively eflect energization of said heater at substantially the start of an oilpeak period in case the temperature of the heat storage mass is below a predetermined value, to prevent energization of th heater at the start of an off-peak period in case the temperature or the heat storage mass is above said predetermined value at the start of an off-peak period and to effect energization of said heater as soon as withdrawal of heat from said heat storage mass causes a reduction or the temperature of said heat storage mass to below said predetermined value, and a normally open switch adapted to be momentarily closed to cause said switching means to energize said heater-during the onpeak period.

CLARK M. OSTERHEID. 

